kernel32 & winelib: Don't test string size in CompareStringW for null terminated strings

[Adam Strzelecki]

Hi,

During playing with installing Visual Studio 2005 with WINE I found  
out that WINE's MSI is spending lot of time inside lstrcmpW. With Mac  
OS X process sampler I checked that actually 60-70% of CompareStringW  
is wine_compare_string, rest is rest of function body, which is in  
case 2 strlenW calls (inline).
I believe this isn't necessary, moreover most of compares in MSI are  
non-matching on first few characters, however with current  
implementation we go trough all strings with strlenW regardless of  
anything, which is waste in CPU cucles.
I modified both CompareStringW and wine_compare_string so they work  
with -1 strings without strlenW checking before.
This saves in my testing about 20-30% of CPU cycles.

Note also that WINE's strlenW and lstrcmpW functions are far from  
perfect. Normal msvcrt or glibc string functions are far more  
optimized at machine code level. This makes strong impact on WINE  
parts strongly relaying on string manipulation which is in this case  
MSI.

Cheers,
-- 
Adam Strzelecki |: nanoant.com :|
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